Electronic devices including magnetic cell core structures

ABSTRACT

A magnetic cell includes a magnetic region formed from a precursor magnetic material comprising a diffusive species and at least one other species. An amorphous region is proximate to the magnetic region and is formed from a precursor trap material comprising at least one attractor species having at least one trap site and a chemical affinity for the diffusive species. The diffusive species is transferred from the precursor magnetic material to the precursor trap material where it bonds to the at least one attractor species at the trap sites. The species of the enriched trap material may intermix such that the enriched trap material becomes or stays amorphous. The depleted magnetic material may then be crystallized through propagation from a neighboring crystalline material without interference from the amorphous, enriched trap material. This enables high tunnel magnetoresistance and high magnetic anisotropy strength. Methods of fabrication and semiconductor devices are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/057,909, filed Mar. 1, 2016, now U.S. Pat. No. 10,026,889, issuedJul. 17, 2018, which is a divisional of U.S. patent application Ser. No.14/249,183, filed Apr. 9, 2014, now U.S. Pat. No. 9,281,466, issued Mar.8, 2016, the disclosure of each of which is hereby incorporated in itsentirety herein by this reference.

TECHNICAL FIELD

The present disclosure, in various embodiments, relates generally to thefield of memory device design and fabrication. More particularly, thisdisclosure relates to design and fabrication of memory cellscharacterized as spin torque transfer magnetic random access memory(STT-MRAM) cells, to semiconductor structures employed in such memorycells, and to semiconductor devices incorporating such memory cells.

BACKGROUND

Magnetic Random Access Memory (MRAM) is a non-volatile computer memorytechnology based on magnetoresistance. One type of MRAM cell is a spintorque transfer MRAM (STT-MRAM) cell, which includes a magnetic cellcore supported by a substrate. The magnetic cell core includes at leasttwo magnetic regions, for example, a “fixed region” and a “free region,”with a non-magnetic region between. The free region and the fixed regionmay exhibit magnetic orientations that are either horizontally oriented(“in-plane”) or perpendicularly oriented (“out-of-plane”) relative tothe width of the regions. The fixed region includes a magnetic materialthat has a substantially fixed (e.g., a non-switchable) magneticorientation. The free region, on the other hand, includes a magneticmaterial that has a magnetic orientation that may be switched, duringoperation of the cell, between a “parallel” configuration and an“anti-parallel” configuration. In the parallel configuration, themagnetic orientations of the fixed region and the free region aredirected in the same direction (e.g., north and north, east and east,south and south, or west and west, respectively). In the “anti-parallel”configuration, the magnetic orientations of the fixed region and thefree region are directed in opposite directions (e.g., north and south,east and west, south and north, or west and east, respectively). In theparallel configuration, the STT-MRAM cell exhibits a lower electricalresistance across the magnetoresistive elements (e.g., the fixed regionand free region). This state of low electrical resistance may be definedas a “0” logic state of the MRAM cell. In the anti-parallelconfiguration, the STT-MRAM cell exhibits a higher electrical resistanceacross the magnetoresistive elements. This state of high electricalresistance may be defined as a “1” logic state of the STT-MRAM cell.

Switching of the magnetic orientation of the free region may beaccomplished by passing a programming current through the magnetic cellcore and the fixed and free regions therein. The fixed region polarizesthe electron spin of the programming current, and torque is created asthe spin-polarized current passes through the core. The spin-polarizedelectron current exerts the torque on the free region. When the torqueof the spin-polarized electron current passing through the core isgreater than a critical switching current density (J_(c)) of the freeregion, the direction of the magnetic orientation of the free region isswitched. Thus, the programming current can be used to alter theelectrical resistance across the magnetic regions. The resulting high orlow electrical resistance states across the magnetoresistive elementsenable the write and read operations of the MRAM cell. After switchingthe magnetic orientation of the free region to achieve the one of theparallel configuration and the anti-parallel configuration associatedwith a desired logic state, the magnetic orientation of the free regionis usually desired to be maintained, during a “storage” stage, until theMRAM cell is to be rewritten to a different configuration (i.e., to adifferent logic state).

A magnetic region's magnetic anisotropy (“MA”) is an indication of thedirectional dependence of the material's magnetic properties. Therefore,the MA is also an indication of the strength of the material's magneticorientation and of its resistance to alteration of its orientation.Interaction between certain nonmagnetic material (e.g., oxide material)and magnetic material may induce MA (e.g., increase MA strength) along asurface of the magnetic material, adding to the overall MA strength ofthe magnetic material and the MRAM cell. A magnetic material exhibitinga magnetic orientation with a high MA strength may be less prone toalteration of its magnetic orientation than a magnetic materialexhibiting a magnetic orientation with a low MA strength. Therefore, afree region with a high MA strength may be more stable during storagethan a free region with a low MA strength.

Other beneficial properties of free regions are often associated withthe microstructure of the free regions. These properties include, forexample, the cell's tunnel magnetoresistance (“TMR”). TMR is a ratio ofthe difference between the cell's electrical resistance in theanti-parallel configuration (R_(ap)) and its resistance in the parallelconfiguration (R_(p)) to R_(p) (i.e., TMR=(R_(ap)−R_(p))/R_(p)).Generally, a free region with a consistent crystal structure (e.g., abcc (001) crystal structure) having few structural defects in themicrostructure of its magnetic material has a higher TMR than a thinfree region with structural defects. A cell with high TMR may have ahigh read-out signal, which may speed the reading of the MRAM cellduring operation. High TMR may also enable use of low programmingcurrent.

Efforts have been made to form free regions having high MA strength andhaving microstructures that are conducive for high TMR. However, becausecompositions and fabrication conditions that promote a desirablecharacteristic—such as a characteristic that enables high MA, high TMR,or both—often inhibit other characteristics or performance of the MRAMcell, forming MRAM cells that have both high MA strength and high TMRhas presented challenges.

For example, efforts to form magnetic material at a desired crystalstructure include propagating the desired crystal structure to themagnetic material (referred to herein as the “targeted magneticmaterial”) from a neighboring material (referred to herein as the “seedmaterial”). However, propagating the crystal structure may be inhibited,or may lead to microstructural defects in the targeted magneticmaterial, if the seed material has defects in its crystal structure, ifthe targeted magnetic material has a competing crystal structure to thatof the crystal material, or if competing crystal structures are alsopropagating to the targeted magnetic material from materials other thanthe seed material.

Efforts to ensure that the seed material has a consistent, defect-freecrystal structure that can be successfully propagated to a targetedmagnetic material have included annealing the seed material. However,because both the seed material and the targeted magnetic material areoften simultaneously exposed to the annealing temperatures, while theanneal improves the crystal structure of the seed material, the annealmay also begin crystallization of other materials, including thetargeted magnetic material and other neighboring materials. This othercrystallization can compete with and inhibit the propagation of thedesired crystal structure from the seed material.

Efforts to delay crystallization of the targeted magnetic material,until after the seed material is crystallized into a desired crystalstructure, have included incorporating an additive into the targetedmagnetic material, when initially formed, so that the targeted magneticmaterial is initially amorphous. For example, where the targetedmagnetic material is a cobalt-iron (CoFe) magnetic material, boron (B)may be added so that a cobalt-iron-boron (CoFeB) magnetic material maybe used as a precursor material and formed in an initially-amorphousstate. The additive may diffuse out of the targeted magnetic materialduring the anneal, enabling the targeted magnetic material tocrystallize under propagation from the seed material, after the seedmaterial has crystallized into the desired crystal structure. Whilethese efforts may decrease the likelihood that the targeted magneticmaterial will be initially formed with a microstructure that willcompete with the crystal structure to be propagated from the seedmaterial, the efforts do not inhibit the propagation of competingcrystal structures from neighboring materials other than the seedmaterial. Moreover, the additive diffusing from the targeted magneticmaterial may diffuse to regions within the structure where the additiveinterferes with other characteristics of the structure, e.g., MAstrength. Therefore, forming a magnetic material with a desiredmicrostructure, e.g., to enable a high TMR, while not deterioratingother characteristics of the magnetic material or the resultingstructure, such as MA strength, can present challenges.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional, elevational, schematic illustration of amagnetic cell structure according to an embodiment of the presentdisclosure, wherein the magnetic cell structure includes a fixed regionoverlying a free region, a single oxide region, and a trap regionproximate to the free region.

FIG. 1A is an enlarged view of box lAB of FIG. 1, according to analternate embodiment of the present disclosure, wherein the fixed regionincludes an oxide-adjacent portion, an intermediate portion, and anelectrode-adjacent portion.

FIG. 1B is an enlarged view of box lAB of FIG. 1, according to anotheralternate embodiment of the present disclosure, wherein the fixed regionincludes an oxide-adjacent portion, an intermediate trap portion, and anelectrode-adjacent portion.

FIG. 2 is a cross-sectional, elevational, schematic illustration of amagnetic cell structure according to an embodiment of the presentdisclosure, wherein the magnetic cell structure includes a fixed regionoverlying a free region, dual oxide regions proximate to the freeregion, and a trap region also proximate to the free region.

FIG. 2C is an enlarged view of box 2C of FIG. 2, according to analternate embodiment of the present disclosure, wherein a trap region isspaced from a magnetic region by an intermediate region.

FIG. 3 is a cross-sectional, elevational, schematic illustration of asection of a magnetic cell structure according to an embodiment of thepresent disclosure, wherein a free region and a fixed region exhibitin-plane magnetic orientations.

FIG. 4A is a cross-sectional, elevational, schematic illustration of amagnetic cell structure according to an embodiment of the presentdisclosure, wherein the magnetic cell structure includes a fixed regionunderlying a free region, a single oxide region proximate to the freeregion, and a trap region also proximate to the free region.

FIG. 4B is a cross-sectional, elevational, schematic illustration of amagnetic cell structure according to an embodiment of the presentdisclosure, wherein the magnetic cell structure includes a fixed regionunderlying a free region, a single oxide region proximate to the freeregion, a trap region also proximate to the free region, and anothertrap region proximate to the fixed region.

FIG. 5 is a cross-sectional, elevational, schematic illustration of amagnetic cell structure according to an embodiment of the presentdisclosure, wherein the magnetic cell structure includes a fixed regionunderlying a free region, dual oxide regions, a trap region proximate toone of the dual oxide regions and also proximate to the free region, andanother trap region proximate to the fixed region.

FIG. 5A is an enlarged view of box 5A of FIG. 5, according to analternate embodiment of the present disclosure, wherein discrete trapsub-regions alternate with discrete secondary oxide sub-regions.

FIGS. 6 through 9C are cross-sectional, elevational, schematicillustrations during various stages of processing to fabricate themagnetic cell structures of FIGS. 1, 1A, and 1B, according toembodiments of the present disclosure, wherein:

FIG. 6 is a cross-sectional, elevational, schematic illustration of astructure during a stage of processing, the structure including aprecursor trap material;

FIG. 6A is a cross-sectional, elevational, schematic illustration of thestructure of FIG. 6, with the precursor trap material illustrated infurther detail, according to an embodiment of the present disclosure,wherein the precursor trap material is formed to have a structure ofalternating attracter species;

FIG. 6B is a cross-sectional, elevational, schematic illustration of astage of processing preceding that of FIG. 6, wherein an attractermaterial is bombarded to form the precursor trap material of FIG. 6;

FIG. 6C is a cross-sectional, elevational, schematic illustration of astage of processing preceding that of FIG. 6 and following that of FIG.6A, wherein the structure of alternating attracter species is bombardedto form the precursor trap material of FIG. 6;

FIG. 6D is an enlarged view of box 6D of FIG. 6, according to theembodiment of FIG. 6A or 6C, with a simplified illustration of trapsites of the precursor trap material of FIG. 6;

FIG. 6E is an enlarged view of box 6D of FIG. 6 during a stage ofprocessing subsequent to that of FIG. 6D, wherein a diffused species hasreacted with the trap sites of FIG. 6D to form an enriched intermediatetrap material;

FIG. 6F is an enlarged view of box 6D of FIG. 6 during a stage ofprocessing subsequent to that of FIG. 6E, wherein the attracter speciesand the diffused species in the enriched intermediate trap material ofFIG. 6E have intermixed to form an amorphous trap material;

FIG. 6G is an enlarged view of box 6D, during the stage of processing ofFIG. 6, according to an embodiment in which the precursor trap materialcomprises cobalt (Co), iron (Fe), and tungsten (W);

FIG. 6H is an enlarged view of box 6D, during the stage of processing ofFIG. 6, according to another embodiment in which the precursor trapmaterial comprises ruthenium (Ru) and tungsten (W);

FIG. 7 is a cross-sectional, elevational, schematic illustration of astructure during a stage of processing subsequent to that of FIGS. 6 and6D, and preceding that of FIG. 6E;

FIG. 7A is an enlarged view of box 7A of FIG. 7, with a simplifiedillustration of a diffusive species in a precursor magnetic materialadjacent to the precursor trap material of FIG. 6 and FIG. 6D;

FIG. 8 is a cross-sectional, elevational, schematic illustration of anannealed structure during a stage of processing subsequent to that ofFIGS. 7 and 7A and concurrent with that of FIG. 6F;

FIG. 8A is an enlarged view of box 8A of FIG. 8, with a simplifiedillustration of the diffusive species from the precursor magneticmaterial of FIG. 7A, now as the diffused species in the amorphous trapmaterial of FIG. 6F;

FIG. 9A is a cross-sectional, elevational, schematic illustration of aprecursor structure during a stage of processing subsequent to that ofFIG. 8, according to an embodiment of the present disclosure;

FIG. 9B is a cross-sectional, elevational, schematic illustration of aprecursor structure during a stage of processing subsequent to that ofFIG. 8, according to an alternate embodiment of the present disclosure;and

FIG. 9C is an enlarged view of box 9C of FIG. 9B, illustrating a stageof processing subsequent to that of FIG. 9B.

FIG. 10 is a schematic diagram of an STT-MRAM system including a memorycell having a magnetic cell structure according to an embodiment of thepresent disclosure.

FIG. 11 is a simplified block diagram of a semiconductor devicestructure including memory cells having a magnetic cell structureaccording to an embodiment of the present disclosure.

FIG. 12 is a simplified block diagram of a system implemented accordingto one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

Memory cells, semiconductor structures, semiconductor devices, memorysystems, electronic systems, methods of forming memory cells, andmethods of forming semiconductor structures are disclosed. Duringfabrication of the memory cell, a “diffusive species” is at leastpartially removed from a magnetic material, which may also becharacterized as a “precursor magnetic material,” due to proximity ofthe precursor magnetic material to a “precursor trap material” thatincludes at least one attracter species. The at least one attracterspecies has at least one trap site and has a higher chemical affinityfor the diffusive species compared to a chemical affinity between thediffusive species and other species in the precursor magnetic material.The diffusive species may diffuse from the precursor magnetic materialto the precursor trap material. Therein, the diffused species may bondwith the attracter species at what was the trap site. The removal of thediffusive species from the precursor magnetic material, which forms whatmay be characterized as a “depleted magnetic material,” promotescrystallization of the depleted magnetic material into a desired crystalstructure (e.g., a bcc (001) structure). Moreover, the presence of thediffused species in the precursor trap material, which forms what may becharacterized as an “enriched precursor trap material,” and intermixingof the species of the enriched precursor trap material, may form anenriched trap material that has a microstructure, e.g., an amorphousmicrostructure, that does not adversely impact the magnetic material'sability to crystallize into the desired crystal structure. Thus, thedepleted magnetic material may be crystallized into a microstructurethat enables a memory cell including the depleted magnetic material toexhibit high tunnel magnetoresistance (“TMR”) and to have magneticanisotropy (“MA”) induced, along interfaces of the magnetic material(e.g., the depleted magnetic material), by one or more neighboring oxidematerials.

As used herein, the term “substrate” means and includes a base materialor other construction upon which components, such as those within memorycells, are formed. The substrate may be a semiconductor substrate, abase semiconductor material on a supporting structure, a metalelectrode, or a semiconductor substrate having one or more materials,structures, or regions formed thereon. The substrate may be aconventional silicon substrate or other bulk substrate including asemiconductive material. As used herein, the term “bulk substrate” meansand includes not only silicon wafers, but also silicon-on-insulator(“SOT”) substrates, such as silicon-on-sapphire (“SOS”) substrates orsilicon-on-glass (“SOG”) substrates, epitaxial layers of silicon on abase semiconductor foundation, or other semiconductor or optoelectronicmaterials, such as silicon-germanium (Si_(1-x)Ge_(x), where x is, forexample, a mole fraction between 0.2 and 0.8), germanium (Ge), galliumarsenide (GaAs), gallium nitride (GaN), or indium phosphide (InP), amongothers. Furthermore, when reference is made to a “substrate” in thefollowing description, previous process stages may have been utilized toform materials, regions, or junctions in the base semiconductorstructure or foundation.

As used herein, the term “STT-MRAIVI cell” means and includes a magneticcell structure that includes a magnetic cell core including anonmagnetic region disposed between a free region and a fixed region.The nonmagnetic region may be an electrically insulative (e.g.,dielectric) region, in a magnetic tunnel junction (“MTJ”) configuration.For example, the nonmagnetic region, between the free and fixed regions,may be an oxide region (referred to herein as the “intermediate oxideregion”).

As used herein, the term “secondary oxide region” refers to an oxideregion of an STT-MRAM cell other than the intermediate oxide region. Thesecondary oxide region may be formulated and positioned to inducemagnetic anisotropy (“MA”) with a neighboring magnetic material.

As used herein, the term “magnetic cell core” means and includes amemory cell structure comprising the free region and the fixed regionand through which, during use and operation of the memory cell, currentmay be passed (i.e., flowed) to effect a parallel or anti-parallelconfiguration of the magnetic orientations of the free region and thefixed region.

As used herein, the term “magnetic region” means a region that exhibitsmagnetism. A magnetic region includes a magnetic material and may alsoinclude one or more non-magnetic materials.

As used herein, the term “magnetic material” means and includesferromagnetic materials, ferrimagnetic materials, antiferromagnetic, andparamagnetic materials.

As used herein, the terms “CoFeB material” and “CoFeB precursormaterial” mean and include a material comprising cobalt (Co), iron (Fe),and boron (B) (e.g., Co_(x)Fe_(y)B_(z), wherein x=10 to 80, y=10 to 80,and z=0 to 50). A CoFeB material or a CoFeB precursor material may ormay not exhibit magnetism, depending on its configuration (e.g., itsthickness).

As used herein, the term “species” means and includes an element orelements from the Periodic Table of Elements composing a material. Forexample, and without limitation, in a CoFeB material, each of Co, Fe,and B may be referred to as a species of the CoFeB material.

As used herein, the term “diffusive species” means and includes achemical species of a material, the presence of which in the material isnot necessary or, in at least one instance, desirable for thefunctionality of the material. For example, and without limitation, in aCoFeB material of a magnetic region, B (boron) may be referred to as adiffusive species to the extent that the presence of B in combinationwith Co and Fe is not necessary for the Co and Fe to function as amagnetic material (i.e., to exhibit magnetism). Following diffusion, the“diffusive species” may be referred to as a “diffused species.”

As used herein, the term “depleted,” when used to describe a material,describes a material resulting from removal, in whole or part, of adiffusive species from a precursor material.

As used herein, the term “enriched,” when used to describe a material,describes a material to which the diffused species has been added (e.g.,transferred).

As used herein, the term “precursor,” when referring to a material,region, or structure, means and refers to a material, region, orstructure to be transformed into a resulting material, region, orstructure. For example, and without limitation, a “precursor material”may refer to a material from which a species is to be diffused totransform the precursor material into a depleted material; a “precursormaterial” may refer to a material into which a species is to be diffusedto transform the precursor material into an enriched material; a“precursor material” may refer to an unsaturated material having trapsites with which a species is to be chemically bonded to convert the“precursor material” into a material in which the once-available trapsites are now occupied by the species; and “a precursor structure” mayrefer to a structure of materials or regions to be patterned totransform the precursor structure into a resulting, patterned structure.

As used herein, unless the context indicates otherwise, the term “formedfrom,” when describing a material or region, refers to a material orregion that has resulted from an act that produced a transformation of aprecursor material or precursor region.

As used herein, the term “chemical affinity” means and refers to theelectronic property by which dissimilar chemical species tend to formchemical compounds. Chemical affinity may be indicated by the heat offormation of the chemical compound. For example, a first materialdescribed as having a higher chemical affinity for a diffusive speciesof a second material compared to the chemical affinity between thediffusive species and other species of the second material means andincludes that a heat of formation of a chemical compound that includesthe diffusive species and at least one species from the first materialis lower than a heat of formation of a chemical compound that includesthe diffusive species and the other species of the second material.

As used herein, the term “unsaturated material” means and refers to amaterial comprising atoms having at least one trap site.

As used herein, the term “trap site” means and refers to at least one ofan under-coordinated, frustrated, or dangling bond or point defect of anatom or structure of the material comprising the trap site. For example,and without limitation, a “trap site” includes an unsatisfied valence onan atom. Due to the unsatisfied coordination or valency, the trap siteis highly reactive, and, in case of covalent bonding, the unpairedelectrons of the dangling bond react with electrons in other atoms inorder to fill the valence shell of the atom. The atom with a trap sitemay be a free radical in an immobilized material, e.g., a solid.

As used herein, the term “amorphous,” when referring to a material,means and refers to a material having a noncrystalline structure. Forexample, and without limitation, an “amorphous” material includes glass.

As used herein, the term “fixed region” means and includes a magneticregion within the STT-MRAM cell that includes a magnetic material andthat has a fixed magnetic orientation during use and operation of theSTT-MRAM cell in that a current or applied field effecting a change inthe magnetization direction of one magnetic region (e.g., the freeregion) of the cell core may not effect a change in the magnetizationdirection of the fixed region. The fixed region may include one or moremagnetic materials and, optionally, one or more non-magnetic materials.For example, the fixed region may be configured as a syntheticantiferromagnet (SAF) including a sub-region of ruthenium (Ru) adjoinedby magnetic sub-regions. Alternatively, the fixed region may beconfigured with structures of alternating sub-regions of magneticmaterial and coupler material. Each of the magnetic sub-regions mayinclude one or more materials and one or more regions therein. Asanother example, the fixed region may be configured as a single,homogeneous magnetic material. Accordingly, the fixed region may haveuniform magnetization, or sub-regions of differing magnetization that,overall, effect the fixed region having a fixed magnetic orientationduring use and operation of the STT-MRAM cell.

As used herein, the term “coupler,” when referring to a material,region, or sub-region, means and includes a material, region, orsub-region formulated or otherwise configured to antiferromagneticallycouple neighboring magnetic materials, regions, or sub-regions.

As used herein, the term “free region” means and includes a magneticregion within the STT-MRAM cell that includes a magnetic material andthat has a switchable magnetic orientation during use and operation ofthe STT-MRAM cell. The magnetic orientation may be switched between aparallel configuration and an anti-parallel configuration by theapplication of a current or applied field.

As used herein, “switching” means and includes a stage of use andoperation of the memory cell during which programming current is passedthrough the magnetic cell core of the STT-MRAM cell to effect a parallelor anti-parallel configuration of the magnetic orientations of the freeregion and the fixed region.

As used herein, “storage” means and includes a stage of use andoperation of the memory cell during which programming current is notpassed through the magnetic cell core of the STT-MRAM cell and in whichthe parallel or anti-parallel configuration of the magnetic orientationsof the free region and the fixed region is not purposefully altered.

As used herein, the term “vertical” means and includes a direction thatis perpendicular to the width and length of the respective region.“Vertical” may also mean and include a direction that is perpendicularto a primary surface of the substrate on which the STT-MRAM cell islocated.

As used herein, the term “horizontal” means and includes a directionthat is parallel to at least one of the width and length of therespective region. “Horizontal” may also mean and include a directionthat is parallel to a primary surface of the substrate on which theSTT-MRAM cell is located.

As used herein, the term “sub-region,” means and includes a regionincluded in another region. Thus, one magnetic region may include one ormore magnetic sub-regions, i.e., sub-regions of magnetic material, aswell as non-magnetic sub-regions, i.e., sub-regions of non-magneticmaterial.

As used herein, the term “between” is a spatially relative term used todescribe the relative disposition of one material, region, or sub-regionrelative to at least two other materials, regions, or sub-regions. Theterm “between” can encompass both a disposition of one material, region,or sub-region directly adjacent to the other materials, regions, orsub-regions and a disposition of one material, region, or sub-regionindirectly adjacent to the other materials, regions, or sub-regions.

As used herein, the term “proximate to” is a spatially relative termused to describe disposition of one material, region, or sub-region nearto another material, region, or sub-region. The term “proximate”includes dispositions of indirectly adjacent to, directly adjacent to,and internal to.

As used herein, reference to an element as being “on” or “over” anotherelement means and includes the element being directly on top of,adjacent to, underneath, or in direct contact with the other element. Italso includes the element being indirectly on top of, adjacent to,underneath, or near the other element, with other elements presenttherebetween. In contrast, when an element is referred to as being“directly on” or “directly adjacent to” another element, there are nointervening elements present.

As used herein, other spatially relative terms, such as “below,”“lower,” “bottom,” “above,” “upper,” “top,” and the like, may be usedfor ease of description to describe one element's or feature'srelationship to another element(s) or feature(s) as illustrated in thefigures. Unless otherwise specified, the spatially relative terms areintended to encompass different orientations of the materials inaddition to the orientation as depicted in the figures. For example, ifmaterials in the figures are inverted, elements described as “below” or“under” or “on bottom of” other elements or features would then beoriented “above” or “on top of” the other elements or features. Thus,the term “below” can encompass both an orientation of above and below,depending on the context in which the term is used, which will beevident to one of ordinary skill in the art. The materials may beotherwise oriented (rotated 90 degrees, inverted, etc.) and thespatially relative descriptors used herein interpreted accordingly.

As used herein, the terms “comprises,” “comprising,” “includes,” and/or“including” specify the presence of stated features, regions, stages,operations, elements, materials, components, and/or groups, but do notpreclude the presence or addition of one or more other features,regions, stages, operations, elements, materials, components, and/orgroups thereof.

As used herein, “and/or” includes any and all combinations of one ormore of the associated listed items.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

The illustrations presented herein are not meant to be actual views ofany particular material, species, structure, device, or system, but aremerely idealized representations that are employed to describeembodiments of the present disclosure.

Embodiments are described herein with reference to cross-sectionalillustrations that are schematic illustrations. Accordingly, variationsfrom the shapes of the illustrations as a result, for example, ofmanufacturing techniques and/or tolerances, are to be expected. Thus,embodiments described herein are not to be construed as limited to theparticular shapes or regions as illustrated but may include deviationsin shapes that result, for example, from manufacturing techniques. Forexample, a region illustrated or described as box-shaped may have roughand/or nonlinear features. Moreover, sharp angles that are illustratedmay be rounded. Thus, the materials, features, and regions illustratedin the figures are schematic in nature and their shapes are not intendedto illustrate the precise shape of a material, feature, or region and donot limit the scope of the present claims.

The following description provides specific details, such as materialtypes and processing conditions, in order to provide a thoroughdescription of embodiments of the disclosed devices and methods.However, a person of ordinary skill in the art will understand that theembodiments of the devices and methods may be practiced withoutemploying these specific details. Indeed, the embodiments of the devicesand methods may be practiced in conjunction with conventionalsemiconductor fabrication techniques employed in the industry.

The fabrication processes described herein do not form a completeprocess flow for processing semiconductor device structures. Theremainder of the process flow is known to those of ordinary skill in theart. Accordingly, only the methods and semiconductor device structuresnecessary to understand embodiments of the present devices and methodsare described herein.

Unless the context indicates otherwise, the materials described hereinmay be formed by any suitable technique including, but not limited to,spin coating, blanket coating, chemical vapor deposition (“CVD”), atomiclayer deposition (“ALD”), plasma enhanced ALD, physical vapor deposition(“PVD”) (e.g., sputtering), or epitaxial growth. Depending on thespecific material to be formed, the technique for depositing or growingthe material may be selected by a person of ordinary skill in the art.

Unless the context indicates otherwise, the removal of materialsdescribed herein may be accomplished by any suitable techniqueincluding, but not limited to, etching, ion milling, abrasiveplanarization, or other known methods.

Reference will now be made to the drawings, where like numerals refer tolike components throughout. The drawings are not necessarily drawn toscale.

A memory cell is disclosed. The memory cell includes a magnetic cellcore that includes an amorphous region proximate to a magnetic region.The amorphous region is formed from a precursor trap material thatcomprises at least one attracter species having at least one trap site.The attracter species has a chemical affinity for a diffusive species ofa precursor magnetic material from which the magnetic region is formed.Therefore, the attracter species is selected to attract the diffusivespecies from the precursor magnetic material, and the precursor trapmaterial is configured, with its trap sites, to provide sites at whichthe diffused species may react with and bond to the attracter species.

To promote the presence of trap sites in the precursor trap material,the precursor trap material may be configured to include alternatingsub-regions of a plurality of attracter species, such that trap sitesare prevalent at multiple interfaces between the sub-regions.Alternatively or additionally, the presence of trap sites may bepromoted by bombarding the precursor trap material, e.g., with a“bombarding species,” to form additional trap sites in the material. Theincreased concentration of trap sites of one or more attracter speciesin the precursor trap material configures the precursor trap material toattract the diffusive species from the precursor magnetic material andto retain, at least substantially, the diffused species in the enrichedtrap material.

The removal of the diffusive species from the precursor magneticmaterial may enable and improve crystallization of the depleted magneticmaterial. For example, once the diffusive species has been removed fromthe precursor magnetic material, a crystalline structure may propagateto the depleted magnetic material from a neighboring crystallinematerial, e.g., a crystalline oxide material. Moreover, the enrichedtrap material may remain or become amorphous, once the diffused speciesintermixes with the at least one attracter species and any other speciesof the enriched trap material, if present. The amorphous nature of theenriched trap material may not compete with or otherwise negativelyimpact the propagation of the crystal structure from the adjacentcrystalline material to the depleted magnetic material. In someembodiments, the enriched trap material may be amorphous even at hightemperatures (e.g., greater than about 300° C., e.g., greater than about500° C.). Therefore, a high-temperature anneal may be used to promotethe crystallization of the depleted magnetic material withoutcrystallizing the enriched trap material. The crystallization of thedepleted magnetic material may enable a high TMR (e.g., greater thanabout 100%, e.g., greater than about 200%). Moreover, the retention ofthe diffused species in the enriched trap material, via theonce-available trap sites may inhibit the diffused species frominterfering with MA-inducement along the interface between the magneticregion and an adjacent intermediate oxide region. Without being limitedto any one theory, it is contemplated that bonds between the nonmagneticand magnetic materials (e.g., between iron (Fe), in the magnetic region,and oxygen (O) in the nonmagnetic region, i.e., iron-oxygen (Fe—O)bonds), may contribute to the MA strength. Less or no diffusive speciesat the interface may enable more MA-inducing bonds to be formed.Therefore, the lack of interference by the diffused species with theMA-inducing bonds may enable high MA strength. Thus, a magnetic memorycell, with an amorphous, enriched trap region formed from a precursortrap material having trap sites, may be formed with both high TMR andhigh MA strength.

FIG. 1 illustrates an embodiment of a magnetic cell structure 100according to the present disclosure. The magnetic cell structure 100includes a magnetic cell core 101 over a substrate 102. The magneticcell core 101 may be disposed between an upper electrode 104 and a lowerelectrode 105. The magnetic cell core 101 includes a magnetic region andanother magnetic region, for example, a “fixed region” 110 and a “freeregion” 120, respectively, with an oxide region (e.g., an “intermediateoxide region” 130) between. The intermediate oxide region 130 may beconfigured as a tunnel region and may contact the fixed region 110 alonginterface 131 and may contact the free region 120 along interface 132.

Either or both of the fixed region 110 and the free region 120 may beformed homogeneously or, optionally, may be formed to include more thanone sub-region. For example, with reference to FIG. 1A, in someembodiments, a fixed region 110′ of the magnetic cell core 101 (FIG. 1)may include multiple portions. For example, the fixed region 110′ mayinclude a magnetic sub-region as an oxide-adjacent portion 113. Anintermediate portion 115, such as a conductive sub-region, may separatethe oxide-adjacent portion 113 from an electrode-adjacent portion 117.The electrode-adjacent portion 117 may include an alternating structureof magnetic sub-regions 118 and coupler sub-regions 119.

With continued reference to FIG. 1, one or more lower intermediaryregions 140 may, optionally, be disposed under the magnetic regions(e.g., the fixed region 110 and the free region 120), and one or moreupper intermediary regions 150 may, optionally, be disposed over themagnetic regions of the magnetic cell structure 100. The lowerintermediary regions 140 and the upper intermediary regions 150, ifincluded, may be configured to inhibit diffusion of species between thelower electrode 105 and overlying materials and between the upperelectrode 104 and underlying materials, respectively, during operationof the memory cell.

The free region 120 is formed proximate to a trap region 180. The trapregion 180 is formed from a precursor trap material comprising at leastone attracter species that had trap sites. The precursor trap materialis also referred to herein as an “unsaturated attracter material.” Thetrap sites may be formed as the result of, for example and withoutlimitation, a mismatched lattice structure of alternating sub-regions ofattracter species, bombarding an attracter material with a bombardingspecies (e.g., ion and plasma) to form the trap sites (i.e., by breakingexisting bonds), or both.

The attracter species is formulated to have a higher chemical affinityfor a diffusive species from a precursor magnetic material, neighboringthe attracter species, than the chemical affinity between other speciesof the neighboring, precursor magnetic material and the diffusivespecies. The initial presence of the diffusive species in the precursormagnetic material may inhibit crystallization of the precursor magneticmaterial, but the proximity of the trap region 180 to the precursormagnetic material may enable diffusion of the diffusive species from theprecursor magnetic material to material of the trap region 180. Oncediffused, the diffused species may chemically react with the attracterspecies at what were the trap sites.

The removal of the diffusive species from the precursor magneticmaterial leaves a depleted magnetic material (i.e., a magnetic materialwith a lower concentration of the diffusive species compared to aconcentration before diffusion) that is able to crystallize into adesired crystal structure (e.g., a bcc (001)). The desired crystalstructure may be propagated from one or more neighboring materials,e.g., the oxide of the intermediate oxide region 130. The crystallized,depleted magnetic material, having the desired crystal structure, mayexhibit high TMR (e.g., greater than about 100% (about 1.00), e.g.,greater than about 200% (about 2.00).

In some embodiments, the trap region 180 may be formulated to beamorphous and remain amorphous while the neighboring depleted magneticmaterial crystallizes. In some such embodiments, precursor material ofthe trap region 180 may be non-amorphous, i.e., crystalline, wheninitially formed, but the precursor material may be converted into anamorphous structure once the diffused species, from the precursormagnetic material, has been received and intermixed with the precursormaterial of trap region 180, e.g., during an anneal. In otherembodiments, the precursor material of the trap region 180 may beamorphous when initially formed and may remain amorphous even at hightemperatures, e.g., during an anneal, and even once enriched with thediffused species. Thus, the material of the trap region 180 may notinhibit the crystallization of the neighboring depleted magneticmaterial.

The thickness, composition, and structure of the trap region 180 may beselected to provide a sufficient amount of unsaturated attractermaterial (i.e., a sufficient number of trap sites) in the trap region180 to have a desired capacity to receive and bond with the diffusedspecies from the neighboring precursor magnetic material. A thicker trapregion may have a relatively higher capacity for the diffused species,compared to a thinner trap region. According to an embodiment such asthat illustrated in FIG. 1, the trap region 180 may be between about 10Å (about 1.0 nm) to about 100 Å (about 10.0 nm) in thickness.

With reference to FIG. 1B, in some embodiments, additional trap regionsmay be present. For example, another trap region 182 may be included inthe magnetic cell core 101 (FIG. 1). The another trap region 182 may beproximate to magnetic material (e.g., the precursor magnetic material,initially, and, subsequently, the depleted magnetic material) of a fixedregion 110″. In some embodiments, the another trap region 182 may forman intermediate portion of the fixed region 110″, between anoxide-adjacent portion 114 and the electrode-adjacent portion 117.

The another trap region 182 also includes at least one attracterspecies, which may be the same as or different than the attracterspecies of the trap region 180 adjacent the free region 120. The atleast one attracter species of the another trap region 182 alsoincluded, prior to receipt of a diffused species, trap sites. Thus, theanother trap region 182 may be formulated, structured, and disposed soas to attract a diffusive species from a neighboring precursor magneticmaterial (e.g., of the oxide-adjacent portion 114) and to react with thediffused species, to promote crystallization of the depleted magneticmaterial. The another trap region 182 may be amorphous, e.g., once thediffused species has bonded to the attracter species and the attracterand diffused species have intermixed. The another trap region 182, thusenriched with the diffused species, may remain amorphous as theneighboring depleted magnetic material crystallizes, so as to notinterfere with the crystallization.

With continued reference to FIG. 1, in embodiments in which the trapregion 180 is proximate to the free region 120, the trap region 180 maybe physically isolated from the fixed region 110 by one or more otherregions, e.g., by the free region 120 and the intermediate oxide region130. Therefore, species of the trap region 180 may not chemically reactwith species of the fixed region 110.

In embodiments such as that of FIG. 1B, the another trap region 182,proximate to the fixed region 110″ may be physically isolated from thefree region 120 by one or more other regions, e.g., by theoxide-adjacent portion 114 of the fixed region 110″ and by theintermediate oxide region 130. Therefore, species of the another trapregion 182 may not chemically react with species of the free region 120.

The magnetic cell structure 100 of FIG. 1 is configured as a“top-pinned” memory cell, i.e., a memory cell in which the fixed region110 is disposed over the free region 120. The magnetic cell structure100 also includes a single oxide region, i.e., the intermediate oxideregion 130, which may be configured to induce MA in the free region 120and to function as a tunnel region of a magnetic tunnel junction (MTJ)effected by interaction of the free region 120, the intermediate oxideregion 130, and the fixed region 110.

Alternatively, with reference to FIG. 2, a magnetic cell structure 200,according to an embodiment of the present disclosure, may be configuredas a top-pinned memory cell with a magnetic cell core 201 having dualMA-inducing oxide regions (e.g., the intermediate oxide region 130 and asecondary oxide region 270). In some embodiments, such as thatillustrated in FIG. 2, the secondary oxide region 270 may be formed over(e.g., directly on) a foundation region 260, such that an upper surfaceof the foundation region 260 and a lower surface of the secondary oxideregion 270 may contact one another.

The foundation region 260 may provide a smooth template upon whichoverlying materials, such as material of the secondary oxide region 270,are formed. In some embodiments, the foundation region 260 is formulatedand configured to enable formation of the secondary oxide region 270 toexhibit a crystal structure that enables formation of the free region120, over the secondary oxide region 270, with a desired crystalstructure (e.g., a bcc (001) crystal structure). For example, andwithout limitation, the foundation region 260 may enable the secondaryoxide region 270 to be formed thereon with the bcc (001) crystalstructure or later crystallized into the bcc (001) crystal structure,which structure may be propagated to a depleted magnetic material fromwhich the free region 120 is to be formed.

In some embodiments, the foundation region 260 may be formed directly onthe lower electrode 105. In other embodiments, such as that illustratedin FIG. 2, the foundation region 260 may be formed on the one or morelower intermediary regions 140.

In the magnetic cell core 201, the second of the dual oxide regions,i.e., the secondary oxide region 270, may be disposed proximate to thefree region 120, e.g., adjacent to a surface of the free region 120 thatis opposite a surface of the free region 120 proximate to theintermediate oxide region 130. Thus, the secondary oxide region 270 maybe spaced from the intermediate oxide region 130 by the free region 120.

The trap region 280 may separate the free region 120 from the secondaryoxide region 270. Nonetheless, it is contemplated that the trap region280 may be formed to a thickness that enables MA inducement between thefree region 120 and the secondary oxide region 270, even without thefree region 120 and the secondary oxide region 270 being in directphysical contact. For example, the trap region 280 may be thin (e.g.,less than about 6 Å (less than about 0.6 nm) in thickness (e.g., betweenabout 2.5 Å (about 0.25 nm) and about 5 Å (about 0.5 nm) in height)).Thus, the trap region 280 may not substantially degrade theMA-inducement between the oxide region (e.g., the secondary oxide region270) and the magnetic region (e.g., the free region 120). Accordingly, amagnetic region may be crystallized in a structure that promotes highTMR while an adjacent oxide region promotes high MA strength.

In the top-pinned, dual oxide region configuration of FIG. 2, the fixedregion 110 may, alternatively, be configured as either the fixed region110′ of FIG. 1A or the fixed region 110″ of FIG. 1B, as discussed above.Thus, as with the fixed region 110″ of FIG. 1B, the magnetic cellstructure 200 may include more than one trap region (e.g., the trapregion 280 (FIG. 2) and the another trap region 182 (FIG. 1B)).

With respect to FIG. 2C, in this or in any other magnetic cell structureembodiment disclosed herein, the trap region 280 may be spaced from aneighboring magnetic region (e.g., the free region 120) by one or moreintermediate regions 290. Such intermediate region 290 may be formulatedand configured to allow diffusion of the diffusive species from themagnetic region (e.g., the free region 120) to the trap region 280.

The memory cells of embodiments of the present disclosure may beconfigured as out-of-plane STT-MRAM cells, as in FIGS. 1 and 2, or asin-plane STT-MRAM cells, as illustrated in FIG. 3. “In-plane” STT-MRAMcells include magnetic regions exhibiting a magnetic orientation that ispredominantly oriented in a horizontal direction, while “out-of-plane”STT-MRAM cells, include magnetic regions exhibiting a magneticorientation that is predominantly oriented in a vertical direction. Forexample, as illustrated in FIG. 1, the STT-MRAM cell may be configuredto exhibit a vertical magnetic orientation in at least one of themagnetic regions (e.g., the fixed region 110 and the free region 120).The vertical magnetic orientation exhibited may be characterized byperpendicular magnetic anisotropy (“PMA”) strength. As indicated in FIG.1 by arrows 112 and double-pointed arrows 122, in some embodiments, eachof the fixed region 110 and the free region 120 may exhibit a verticalmagnetic orientation. The magnetic orientation of the fixed region 110may remain directed in essentially the same direction throughoutoperation of the STT-MRAM cell, for example, in the direction indicatedby arrows 112 of FIG. 1. The magnetic orientation of the free region120, on the other hand, may be switched, during operation of the cell,between a parallel configuration and an anti-parallel configuration, asindicated by double-pointed arrows 122 of FIG. 1. As another example, asillustrated in FIG. 3, an in-plane STT-MRAM cell may be configured toexhibit a horizontal magnetic orientation in at least one of themagnetic regions (e.g., a fixed region 310 and a free region 320), asindicated by arrow 312 in the fixed region 310 and double-pointed arrow322 in the free region 320. Though FIG. 3 illustrates only the fixedregion 310, the intermediate oxide region 130, and the free region 320,overlying regions may be those overlying the fixed region 110 of FIGS. 1and 2 and underlying regions may be those underlying the free region 120in FIGS. 1 and 2.

Though in some embodiments, such as that of FIGS. 1 and 2, the fixedregion 110 may overlay the free region 120, in other embodiments, suchas that of FIGS. 4A, 4B, and 5, the fixed region 110 may underlay thefree region 120. For example, and without limitation, in FIG. 4A,illustrated is a magnetic cell structure 400 having a magnetic cell core401 in which a fixed region 410 overlays the lower electrode 105 and, ifpresent, the lower intermediary regions 140. The foundation region 260(FIG. 2) (not illustrated in FIG. 4A) may, optionally, be includedbetween, e.g., the lower electrode 105 (or the lower intermediaryregions 140, if present) and the fixed region 410. The fixed region 410may, for example and without limitation, be configured as amulti-sub-region fixed region 410, with an electrode-adjacent portion417 that may be configured as an alternating structure as in theelectrode-adjacent portion 117 of FIGS. 1A and 1B. The oxide-adjacentportion 113 of, e.g., a homogeneous magnetic material, may overlay theelectrode-adjacent portion 417. A sub-region, such as the intermediateportion 115 of FIG. 1A, may be disposed between the electrode-adjacentportion 417 and the oxide-adjacent portion 113. The intermediate oxideregion 130 may overlay the fixed region 410, and a free region 420 mayoverlay the intermediate oxide region 130.

A trap region 480 may be proximate to at least one of the fixed region410 and the free region 420. For example, as illustrated in FIG. 4A, thetrap region 480 may overlay the free region 420. In other embodiments(not illustrated in FIG. 4A), the trap region 480 or another trap regionmay alternatively or additionally underlay the free region 420 or bedisposed internal to the free region 420.

Regardless, the trap region 480 is formed from a precursor trapmaterial, proximate to a precursor magnetic material (e.g., from whichthe free region 420 is to be formed). The precursor trap materialincludes at least one attracter species, with trap sites, formulated andstructured to attract and react with a diffused species from theprecursor magnetic material to promote crystallization of the depletedmagnetic material into a desired crystal structure that enables highTMR.

The upper electrode 104 and, if present, the upper intermediary regions150 may overlay the trap region 480 and the free region 420. Thus, themagnetic cell structure 400 is configured as a “bottom-pinned” memorycell with a single MA-inducing oxide region (e.g., the intermediateoxide region 130).

With reference to FIG. 4B, an alternate embodiment of a magnetic cellstructure 400′, configured as a bottom-pinned memory cell with a singleMA-inducing oxide region, may include substantially the same structureas the magnetic cell structure 400 of FIG. 4A, but with a fixed region410′ of a magnetic cell core 401′ that includes another trap region 482instead of the intermediate portion 115 of the fixed region 410 of FIG.4A. Therefore, the magnetic cell core 401′ may also include a depletedoxide-adjacent portion 414 instead of the non-depleted, oxide-adjacentportion 113 of FIG. 4A.

With reference to FIG. 5, illustrated is a magnetic cell structure 500also configured as a bottom-pinned memory cell. The illustrated magneticcell structure 500 includes a magnetic cell core 501 having dual oxideregions, e.g., the intermediate oxide region 130 and a secondary oxideregion 570. The secondary oxide region 570 may be beneath the upperelectrode 104 and over both of the free region 420 and the trap region480.

In this, or in any other embodiment described herein, the trap region480 may be incorporated with the secondary oxide region 570, e.g., asone or more sub-regions of the secondary oxide region 570. Such atrap-and-oxide-incorporated region may be referred to herein as a “trapoxide region.” For example, as illustrated in FIG. 5A, a trap oxideregion 578 may include discrete trap sub-regions 480′ inter-disposedwith discrete secondary oxide regions 570′. The discrete trapsub-regions 480′ may nonetheless be formed from precursor trap materialhaving attracter species with trap sites to which the diffused species,having diffused from the precursor magnetic material, may bond.

The trap region (e.g., the trap region 180 (FIG. 1)) of any of theembodiments disclosed herein may be substantially continuous (i.e.,without gaps in the material of the region). In other embodiments,however, a trap region, according to any of the embodiments disclosedherein, may be discontinuous (i.e., may have gaps between the materialof the region).

In any of the embodiments described herein, the relative dispositions ofthe fixed region 110 (FIGS. 1 and 2), 110′ (FIG. 1A), 110″ (FIG. 1B),310 (FIG. 3), 410 (FIG. 4A), 410′ (FIGS. 4B and 5), the intermediateoxide region 130 (FIGS. 1 through 2 and 3 through 5), the free region120 (FIGS. 1 and 2), 320 (FIG. 3), 420 (FIGS. 4A, 4B, and 5), the trapregion or regions 180 (FIG. 1), 182 (FIG. 1B), 280 (FIG. 2), 480 (FIGS.4A, 4B, and 5), 482 (FIGS. 4B and 5), the secondary oxide region 270(FIG. 2), 570 (FIG. 5) (if present), the trap oxide region 578 (FIG. 5A)(if present), and any sub-regions (if present) may be respectivelyreversed. Even if reversed, the intermediate oxide region 130 isdisposed between the free region 120 (FIGS. 1 and 2), 320 (FIG. 3), 420(FIGS. 4A, 4B, and 5) and the fixed region 110 (FIGS. 1 and 2), 110′(FIG. 1A), 110″ (FIG. 1B), 310 (FIG. 3), 410 (FIG. 4A), 410′ (FIGS. 4Band 5) with at least one trap region (e.g., the trap region 180 (FIG.1), the another trap region 182 (FIG. 1B), the trap region 280 (FIG. 2),the trap region 480 (FIGS. 4A, 4B, and 5), the another trap region 482(FIGS. 4B and 5), the trap oxide region 578 (FIG. 5A)) proximate toprecursor magnetic material of at least one of the magnetic regions(e.g., at least one of the free region 120 (FIGS. 1 and 2), 320 (FIG.3), 420 (FIGS. 4A, 4B, and 5) and the fixed region 110 (FIGS. 1 and 2),110′ (FIG. 1A), 110″ (FIG. 1B), 310 (FIG. 3), 410 (FIG. 4A), 410′ (FIGS.4B and 5)).

In other embodiments (not illustrated), a trap region may include aportion that is laterally-adjacent to a magnetic region (e.g., the freeregion 120). The laterally-adjacent portion may be in addition to, or analternative to, a vertically-adjacent portion.

Accordingly, disclosed is a memory cell comprising a magnetic cell core.The magnetic cell core comprises a magnetic region comprising a depletedmagnetic material formed from a precursor magnetic material comprisingat least one diffusive species and at least one other species. Thedepleted magnetic material comprises the at least one other species. Themagnetic cell core also comprises another magnetic region and an oxideregion between the magnetic region and the another magnetic region. Anamorphous region is proximate to the magnetic region. The amorphousregion is formed from a precursor trap material comprising at least oneattracter species that has at least one trap site and a chemicalaffinity for the at least one diffusive species that is higher than achemical affinity of the at least one other species for the at least onediffusive species. The amorphous region comprises the at least oneattracter species bonded to the at least one diffusive species from theprecursor magnetic material.

With reference to FIGS. 6 through 9C, illustrated are stages in a methodof fabricating magnetic cell structures, such as the magnetic cellstructure 100 of FIG. 1, and according to the embodiments of FIGS. 1A,and 1B. As illustrated in FIG. 6, an intermediate structure 600 may beformed with a conductive material 605 formed over the substrate 102, anda precursor trap material 680 over the conductive material 605.Optionally, one or more lower intermediary materials 640 may be formedover the conductive material 605, before forming the precursor trapmaterial 680 thereover.

In other embodiments, such as may be utilized to form the magnetic cellstructure 200 of FIG. 2, or another structure comprising a basesecondary oxide region (e.g., the secondary oxide region 270 (FIG. 2), afoundation material (not shown) may be formed over the conductivematerial 605 and the lower intermediary materials 640, if present. Anoxide material (not shown) may be formed over the foundation material,before forming the precursor trap material 680 thereover.

The conductive material 605, from which the lower electrode 105 (FIGS.1, 2, 4A, 4B, and 5) is formed, may comprise, consist essentially of, orconsist of, for example and without limitation, a metal (e.g., copper,tungsten, titanium, tantalum), a metal alloy, or a combination thereof.

In embodiments in which the optional lower intermediary region 140(FIGS. 1, 2, 4A, 4B, and 5) is formed over the lower electrode 105, thelower intermediary material 640, from which the lower intermediaryregion 140 is formed, may comprise, consist essentially of, or consistof, for example and without limitation, tantalum (Ta), titanium (Ti),tantalum nitride (TaN), titanium nitride (TiN), ruthenium (Ru), tungsten(W), or a combination thereof. In some embodiments, the lowerintermediary material 640, if included, may be incorporated with theconductive material 605 from which the lower electrode 105 (FIGS. 1, 2,4A, 4B, and 5) is to be formed. For example, the lower intermediarymaterial 640 may be an upper-most sub-region of the conductive material605.

In embodiments in which a foundation material is formed over theconductive material, as if forming the magnetic cell structure 200 ofFIG. 2, the foundation material may comprise, consist essentially of, orconsist of, for example and without limitation, a material comprising atleast one of cobalt (Co) and iron (Fe) (e.g., a CoFeB material), amaterial comprising a nonmagnetic material (e.g., a nonmagneticconductive material (e.g., a nickel-based material)), or a combinationthereof. The foundation material may be formulated and configured toprovide a template that enables forming a material (e.g., an oxidematerial) thereover at a desired crystal structure (e.g., a bcc (001)crystal structure).

Also in embodiments to form the magnetic cell structure 200 of FIG. 2,the oxide material, from which the secondary oxide region 270 (FIG. 2)is to be formed, may comprise, consist essentially of, or consist of,for example and without limitation, a nonmagnetic oxide material (e.g.,magnesium oxide (MgO), aluminum oxide (Al₂O₃), titanium oxide (TiO₂), orother oxide materials of conventional MTJ regions). The oxide materialmay be formed (e.g., grown, deposited) directly on the foundationmaterial, if present. In embodiments in which the foundation material isamorphous when initially formed, the resulting oxide material may becrystalline (e.g., have a bcc (001) crystal structure) when initiallyformed over the foundation material.

The precursor trap material 680, may be formed by, for example andwithout limitation, sputtering at least one attracter species over thepreviously-formed materials. The precursor trap material 680 isformulated (i.e., the at least one attracter species is selected) tohave a higher chemical affinity for a diffusive species from a precursormagnetic material, to be formed adjacent the precursor trap material680, compared to a chemical affinity between the diffusive species andanother species of the precursor magnetic material. Therefore, theprecursor trap material 680 is formulated to attract the diffusivespecies from the precursor magnetic material.

In some embodiments, each species of the precursor trap material 680 maybe formulated to have a chemical affinity for (i.e., be compatible tochemically bond with) the diffused species from the precursor magneticmaterial. In other embodiments, fewer than all of the species of theprecursor trap material 680 may be formulated to have the desiredchemical affinity for the diffusive species. Therefore, the precursortrap material 680 may include species non-reactive with the diffusedspecies or may consist of or consist essentially of species that reactwith the diffused species.

With reference to FIGS. 6 through 6F, the precursor trap material 680 isstructured and formulated to provide at least one trap site 687 (FIG.6D) of at least one attracter species 684, 686 (FIGS. 6A and 6C through6F). The trap sites 687 (FIG. 6D) enable the diffusive species, oncediffused from the precursor magnetic material, to bond with at least oneof the at least one attracter species 684, 686 so that the diffusedspecies may be retained in what is referred to herein as an “enrichedprecursor trap material” 681 (FIG. 6E).

Structuring the precursor trap material 680 to include the trap sites687 (FIG. 6D) may include forming the precursor trap material 680 with astructure of mismatched crystal lattices between neighboring sub-regionsof the attracter species 684, 686. As used herein, the term “mismatchedcrystal lattices” refers to crystal lattice structures of neighboringspecies that are not in alignment with one another such that 1:1 bondingbetween the species, to completely saturate the species, is not readilyachievable. For example, with reference to FIGS. 6A and 6D, a pluralityof attracter species 684, 686 may be formed, one over the other, to forman alternating structure with interfaces 685 formed where two of theattracter species 684, 686 adjoin one another. With reference to FIG.6D, such a mismatched crystal lattice structure may leave trap sites 687on atoms 684′, 686′, 686″ of the attracter species 684, 686. The trapsites 687 may particularly occupy the interfaces 685 between speciesdue, at least in part, to the mismatch between crystal latticestructures of the attracter species 684, 686.

Without being limited to any particular theory, it is contemplated thatthe greater the number of interfaces 685, and, thus, the greater thenumber of alternating sub-regions of the attracter species 684, 686, thegreater the number of trap sites 687 that may be included in theprecursor trap material 680. The thickness of each individual sub-regionmay be minimal (e.g., approximately one atom thick or several atomsthick), with the total thickness of such an intermediate structure 600′tailored to provide a maximum number of trap sites 687 (i.e., potentialbonding sites for the diffused species, during subsequent processingacts) without degrading other characteristics (e.g., electricalresistivity) of the cell to be formed.

In some embodiments, the precursor trap material 680 may include atransition metal (e.g., tungsten (W), hafnium (Hf), molybdenum (Mo), andzirconium (Zr)) as at least one of the attracter species 684, 686 (e.g.,attracter species 684 of FIGS. 6A and 6C through 6F) and at least one ofiron (Fe), cobalt (Co), ruthenium (Ru), and nickel (Ni) as at least oneother of the attracter chemicals (e.g., attracter species 686 of FIGS.6A and 6C through 6F).

In one particular example, without limitation, the precursor trapmaterial 680 may comprise, consist essentially of, or consist of cobaltand iron as one type of attracter species (e.g., the attracter species686) and tungsten (W) as another attracter species (e.g., the attracterspecies 684). Each of the cobalt-iron and tungsten may have a chemicalaffinity for a diffusive species, such as boron (B), of a neighboringprecursor magnetic material formulated as a CoFeB magnetic material. Atleast the chemical affinity of the tungsten for the boron may be greaterthan a chemical affinity between the boron and the other species of theprecursor magnetic material (e.g., cobalt and iron).

In another particular example, without limitation, the precursor trapmaterial 680 may comprise, consist essentially of, or consist ofruthenium (Ru) as one attracter species and tungsten (W) as anotherattracter species. Again, each of the ruthenium and the tungsten mayhave a chemical affinity for the diffusive species (e.g., boron (B)).

With reference to FIG. 6B, another method for structuring the precursortrap material 680 to include the trap sites 687 (FIG. 6D) is to form,over the substrate 102, an attracter material 680″, which may notnecessarily be unsaturated when initially formed, and then bombard theattracter material 680″ with, e.g., one or more ions or radicals fromplasma as bombarding species, to induce point defects, frustrated bonds,under-coordinated sites, or dangling bonds (i.e., trap sites) in themicrostructure of the attracter material 680″. For example, bombardingspecies such as argon (Ar), nitrogen (N), helium (He), xenon (Xe) may bedriven into the attracter material 680″ of intermediate structure 600″,as indicated by arrows 688, to break occupied bonds and create the trapsites 687 (FIG. 6D). In such embodiments, the bombarding species may beretained in the precursor trap material 680 (FIGS. 6 and 6D).

With reference to FIG. 6C, a combination of techniques may be utilizedto structure the precursor trap material 680 to include the trap sites687 (FIG. 6D). For example, the intermediate structure 600′ of FIG. 6A,with the mismatched crystal lattice structure, may be subjected to thebombardment 688 process of FIG. 6B. A bombarded mismatched crystallattice intermediate structure 600′″ may include more trap sites 687(FIG. 6D) than may result from the techniques of FIGS. 6A and 6B alone.

During subsequent processing, such as during an anneal stage, adiffusive species 621′ (FIG. 7A) may transfer (e.g., diffuse) from aneighboring precursor magnetic material to the precursor trap material680 during. As this occurs, as illustrated in FIG. 6E, the trap sites687 (FIG. 6D) may receive and react with the diffused species 621 toform an enriched precursor trap material 681. Atoms of the diffusedspecies 621 may bond to one or more of the atoms 684′, 686′, 686″ of theattracter species 684, 686 (see FIG. 6E).

In some embodiments, such as that of FIG. 6A and FIG. 6C and,optionally, also FIG. 6B, the precursor trap material 680 may becrystalline when initially formed over the substrate 102. The precursortrap material 680 may remain crystalline, at least initially, as thediffused species 621 begins to diffuse into and react with the trapsites 687 (FIG. 6D). However, as the composition of enriched precursortrap material 681 changes, i.e., as more of the diffused species 621becomes trapped by the trap sites 687 (FIG. 6D), and as the hightemperatures of the anneal encourage material movement, the species(e.g., the diffused species 621 and the attracter species 684, 686) ofthe enriched precursor trap material 681 may intermix and convert theenriched precursor trap material 681 into an amorphous enriched trapmaterial 682 (also referred to herein as an “enriched trap material 682”and an “enriched amorphous trap material 682”), as illustrated in FIG.6F.

In other embodiments, such as those of FIGS. 6G and 6H, the precursortrap material 680 (FIG. 6) may be formulated to be amorphous wheninitially formed over the substrate 102 and to remain amorphousthroughout, e.g., an anneal. For example, with reference to FIG. 6G, aprecursor trap material 680 ^(IV) may comprise, consist essentially of,or consist of iron (Fe), cobalt (Co), and tungsten (W) and may beamorphous when initially formed over the substrate 102 (FIG. 6). Atleast one of the atoms of the Fe, Co, and W may be under-coordinated,frustrated, or have dangling bonds or point defects such that the atomsinclude trap sites 687 (see FIG. 6D) (not illustrated in FIG. 6G). Asanother example, with reference to FIG. 6H, a precursor trap material680 ^(V) may comprise, consist essentially of, or consist of ruthenium(Ru) and tungsten (W) and may be amorphous when initially formed overthe substrate 102 (FIG. 6). At least one of the atoms of the Ru and Wmay be under-coordinated, frustrated, or having dangling bonds or pointdefects such that the atoms include trap sites 687 (see FIG. 6D) (notillustrated in FIG. 6H). In either such embodiment, the trap sites 687(see FIG. 6D) may not be aligned along defined interfaces, but, rather,may be distributed throughout the precursor trap material 680 ^(IV)(FIG. 6G), 680 ^(V) (FIG. 6H). Moreover, the enriched precursor trapmaterial 681 may also be amorphous. In such embodiments, the atomicratios of the species of the precursor trap material 680 ^(IV) (FIG.6G), 680 ^(V) (FIG. 6H) may be selected to enable the precursor trapmaterial 680 ^(IV) (FIG. 6G), 680 ^(V) (FIG. 6H) to be amorphous andremain amorphous even at high anneal temperatures (e.g., greater thanabout 500° C.).

In any case, the atomic ratios of the attracter species 684, 686 in theprecursor trap material 680 may be selected to tailor the atomic ratiosin the final, enriched trap material 682 to a composition that will beamorphous and remain amorphous at high anneal temperatures. For example,in embodiments in which the precursor trap material 680 comprises,consists essentially of, or consists of iron (Fe), cobalt (Co), andtungsten (W) and in which boron (B) is the diffused species 621, thecomposition of the precursor trap material 680 may be selected so thatthe composition of the enriched trap material 682, including thediffused species 621 and, optionally, bombarding species, comprises atleast about 35 at.% tungsten (W), which may remain amorphous up totemperatures of about 700° C.

Moreover, the precursor trap material 680 may be formulated such thatthe precursor trap material 680 is stable (e.g., species will notout-diffuse) at high temperatures used during anneal for crystallizingthe depleted magnetic material. Therefore, the high temperatures thatpromote crystallization of the depleted magnetic material, derived froma precursor magnetic material, to a desired crystal structure (e.g., abcc (001) structure) may be utilized without the precursor trap material680 inhibiting the crystallization. Without being limited to any onetheory, it is contemplated that the amorphous nature of the enrichedtrap material 682 avoids microstructure defects in the depleted magneticmaterial that may otherwise form if the enriched trap material 682 had amicrostructure that differed from and competed with that of the desiredcrystal structure (e.g., the bcc (001) structure) as the crystalstructure propagated to the depleted magnetic material from aneighboring material.

Accordingly, disclosed is a semiconductor structure comprising amagnetic region over a substrate. The magnetic region comprises aprecursor magnetic material comprising a diffusive species. A trapregion comprises at least one attracter species, which comprises atleast one trap site. The at least one attracter species is formulated toexhibit a higher chemical affinity for the diffusive species of themagnetic precursor material than a chemical affinity between thediffusive species and another species of the precursor magneticmaterial.

With reference to FIG. 7, after the precursor trap material 680 of FIG.6 has been formed, and before diffusion of the diffusive species 621′ toreact with the trap sites 687 (FIGS. 6D and 6E), at least one precursormagnetic material 720 may be formed over the precursor trap material680, as illustrated in FIG. 7. The precursor magnetic material 720, fromwhich the free region 120 (FIG. 1) is eventually formed, may comprise,consist essentially of, or consist of, for example and withoutlimitation, a ferromagnetic material including cobalt (Co) and iron (Fe)(e.g. Co_(x)Fe_(y), wherein x=10 to 80 and y=10 to 80) and, in someembodiments, also boron (B) (e.g., Co_(x)Fe_(y)B_(z), wherein x=10 to80, y=10 to 80, and z=0 to 50). Thus, the precursor magnetic material720 may comprise at least one of Co, Fe, and B (e.g., a CoFeB material,a FeB material, a CoB material). In other embodiments, the precursormagnetic material 720 may alternatively or additionally include nickel(Ni) (e.g., an NiB material). In some embodiments, the precursormagnetic material 720 may comprise the same material as the foundationmaterial, if included over the conductive material 605 on the substrate102, or a material having the same elements as the foundation material,though with different atomic ratios of those elements. The precursormagnetic material 720 may be formed as a homogeneous region. In otherembodiments, the precursor magnetic material 720 may include one or moresub-regions, e.g., of CoFeB material, with the sub-regions havingdifferent relative atomic ratios of Co, Fe, and B.

With reference to FIG. 7A, the precursor magnetic material 720 includesat least one diffusive species 621′ and at least one other species. Thepresence of the diffusive species 621′ is not necessary for theprecursor magnetic material 720, or a depleted magnetic material formedtherefrom, to exhibit magnetism. However, the presence of the diffusivespecies 621′ in the precursor magnetic material 720 may enable theprecursor magnetic material 720 to be formed (e.g., by sputtering) in anamorphous state.

The proximity of the precursor trap material 680 to the precursormagnetic material 720 and the precursor trap material's 680 higherchemical affinity for the diffusive species 621′ (FIG. 7A) compared tothe other species of the precursor magnetic material 720, may enableremoval of the diffusive species 621′ (FIG. 7A) from the precursormagnetic material 720. With reference to FIGS. 8 and 8A, the removalforms a depleted magnetic material 820 and the enriched trap material682, as illustrated in FIG. 8. For example, and with reference to FIG.8B, the diffusive species 621′ (FIG. 7A) may diffuse into the precursortrap material 680 where the diffused species 621 may chemically bond tothe attracter species 684, 686 of the precursor trap material 680. Thisremoval of the diffused species 621 from the precursor magnetic material720 by the precursor trap material 680 may occur during an anneal of anintermediate structure 700 (FIG. 7) to form an annealed intermediatestructure 800, as illustrated in FIG. 8.

In the annealed intermediate structure 800, the depleted magneticmaterial 820 has a lower concentration of the diffused species 621 (FIG.8A), while the enriched trap material 682 includes the diffused species621, as illustrated in FIG. 8A. The magnetic cell structures 100 (FIG.1), 200 (FIG. 2), 400 (FIG. 4A), 400′ (FIG. 4B), and 500 (FIG. 5) maythus include the depleted magnetic material 820 (e.g., in the freeregion 120 (FIGS. 1 and 2), 320 (FIG. 3), 420 (FIGS. 4A, 4B, and 5); inthe oxide-adjacent portion 114 of the fixed region 110″ (FIG. 1B); andin the oxide-adjacent portion 414 of the fixed region 410′ (FIGS. 4 and5)) and the diffused-species-including enriched trap material 682 (e.g.,in the trap region 180 (FIG. 1), 280 (FIGS. 2 and 2C); 480 (FIGS. 4A,4B, and 5), in the another trap region 182 (FIG. 1B), 482 (FIGS. 4B and5); in the discrete trap sub-regions 480′ of the trap oxide region 578(FIG. 5A)).

For example, and without limitation, in embodiments in which theprecursor magnetic material 720 (FIG. 7) is a CoFeB material, thedepleted magnetic material 820 may be a CoFe material (i.e., a magneticmaterial comprising cobalt and iron). In such embodiments in which theprecursor trap material 680 (FIG. 7) is an alternating structure ofsub-regions of a cobalt-iron (CoFe) attracter species and sub-regions ofa tungsten (W) attracter species, the enriched trap material 682 may bean amorphous mixture of cobalt, iron, tungsten, and boron (B) (i.e., aCoFeWB mixture or alloy).

Without being restricted to any one theory, it is contemplated thatremoving the diffusive species 621′ (FIG. 7A) of boron from the CoFeBprecursor magnetic material 720 with a precursor trap material 680having trap sites 687 (FIG. 6D) of attracter species having an affinityfor boron may enable crystallization of the depleted magnetic material820 at a lower temperature than the crystallization temperature of theprecursor magnetic material 720 (FIG. 7) including the diffusive species621′. Thus, an anneal temperature used (e.g., greater than about 500°C.) may enable crystallization of the depleted magnetic material 820(e.g., by propagating the desired crystal structure from a neighboringmaterial, e.g., material of the intermediate oxide region 130 (FIG. 1))without being so high as to degrade neighboring materials (e.g., withoutout-diffusing tungsten (W) from the enriched trap material 682). Thedepleted magnetic material 820 may, therefore, be crystallized into adesired crystal structure (e.g., a bcc (001) crystal structure) thatenables formation of a magnetic cell structure (e.g., the magnetic cellstructure 100 (FIG. 1), 200 (FIG. 2), 400 (FIG. 4A), 400′ (FIG. 4B), 500(FIG. 5)) without suffering from substantial structural defects. Theabsence of substantial structural defects may enable a high TMR.

Without being limited to any one theory, it is further contemplated thatremoval of the diffusive species 621′ (FIG. 7A) from the precursormagnetic material 720 (and/or from another precursor magnetic material713′ (FIG. 9B)) may also promote inducement of MA along an interfacebetween the depleted magnetic material 820 and a neighboring oxidematerial (e.g., the oxide material of the secondary oxide region 270(FIG. 2) or the intermediate oxide region 130 (FIG. 1)). For example, inthe absence of the diffusive species 621′ (FIG. 7A), the other speciesof the depleted magnetic material 820 may have more interaction with theoxide material than the other species would have if the diffusivespecies 621′ were still incorporated in the precursor magnetic material720. Moreover, the retention of the diffused species 621 (FIG. 8A) viachemical bonds at the once-available trap sites 687 (FIG. 6D) in theenriched trap material 682 may avoid the diffused species 621 fromdiffusing to the interface (e.g., interface 132 (FIG. 1)) between themagnetic region (e.g., the free region 120) and its neighboringMA-inducing oxide region (e.g., the intermediate oxide region 130 (FIG.1)). This may enable more MA-inducing interaction along the interface(e.g., interface 132 (FIG. 1)) than may otherwise be achieved.Therefore, even in embodiments in which only a single MA-inducing oxideregion (e.g., the intermediate oxide region 130) is included, the MAstrength may be greater, due to the presence of the precursor trapmaterial 680 (or, rather, the enriched trap material 682) than the MAstrength of the same structure without the precursor trap material 680(or, rather, the enriched trap material 682).

While the free region 120 (e.g., FIG. 1) is described as being “formedfrom” the precursor magnetic material 720 (e.g., a CoFeB material) thatcomprises the diffusive species 621′ (FIG. 7A), the free region 120 ofthe fabricated, magnetic cell core 101 (FIG. 1) (or any cell core of thepresent disclosure) may comprise substantially less of the diffusivespecies 621′ (e.g., the boron (B)) than when the precursor magneticmaterial 720 was initially formed. Likewise, in embodiments in whichmagnetic material of the fixed region 110 (FIG. 1) is affected by aneighboring region of a trap material, the fixed region 110 may comprisesubstantially less of the diffusive species 621′ than it would withoutthe nearby trap material. Rather, the trap region 180 (FIG. 1) of thefabricated, magnetic cell core 101 may comprise both the species of theprecursor trap material 680 and the diffused species 621 (e.g., theboron (B)), which has diffused from the precursor magnetic material 720.

With continued reference to FIGS. 7 and 8, an oxide material 730, fromwhich the intermediate oxide region 130 (FIG. 1) is formed, may beformed on the precursor magnetic material 720, e.g., before the annealthat crystallizes the depleted magnetic material 820. The oxide material730 may comprise, consist essentially of, or consist of, for example andwithout limitation, a nonmagnetic oxide material (e.g., magnesium oxide(MgO), aluminum oxide (Al₂O₃), titanium oxide (TiO₂), or other oxidematerials of conventional MTJ nonmagnetic regions). In embodiments inwhich another oxide material was formed before the precursor trapmaterial 680, the another oxide material may be the same material as theoxide material 730 or a material comprising the same elements as theoxide material 730 though with different atomic ratios thereof. Forexample, and without limitation, both of the oxide material 730 andanother oxide material, in a dual-oxide embodiment, may comprise,consist essentially of, or consist of MgO.

The oxide material 730 may be formed (e.g., grown, deposited) directlyon the precursor magnetic material 720. The oxide material 730 may becrystalline (e.g., with the bcc (001) structure) when initially formedor may later be crystallized during anneal. The oxide material 730 maybe positioned such that, during anneal, the desired crystal structuremay propagate to a neighboring magnetic material (e.g., the depletedmagnetic material 820 (FIG. 8)) to enable the magnetic material (e.g.,the depleted magnetic material 820 (FIG. 8)) to crystallize into thesame crystal structure (e.g., the bcc (001) structure).

Other materials of the annealed intermediate structure 800 may also becrystallized due to annealing. The annealing process may be conducted atan annealing temperature of from about 300° C. to about 700° C. (e.g.,about 500° C.) and may be held at the annealing temperature for fromabout one minute (about 1 min.) to about one hour (about 1 hr.). Theannealing temperature and time may be tailored based on the materials ofthe intermediate structure 700, the desired crystal structure of, e.g.,the depleted magnetic material 820, and a desired amount of depletion ofthe diffused species 621 from the precursor magnetic material 720.

In some embodiments, such as that illustrated in FIGS. 7 and 8, theanother magnetic material 713, from which the oxide-adjacent portion 113of the fixed region 110′ (FIG. 1A) is formed, may be formed (e.g.,grown, deposited) directly on the oxide material 730, e.g., before orafter the anneal stage that crystallizes the depleted magnetic material820. The another magnetic material 713 may comprise, consist essentiallyof, or consist of, for example and without limitation, ferromagneticmaterial including cobalt (Co) and iron (Fe) (e.g., Co_(x)Fe_(y),wherein x=10 to 80 and y=10 to 80) and, in some embodiments, also boron(B) (e.g., Co_(x)Fe_(y)B_(z), wherein x=10 to 80, y=10 to 80, and z=0 to50). Thus, the another magnetic material 713 may comprise a CoFeBmaterial. In some embodiments, the another magnetic material 713 may bethe same material as either or both of precursor magnetic material 720and the foundation material, if included in the intermediate structure800, or a material having the same elements, though in different atomicratios.

With reference to FIG. 9A, according to an embodiment to form themagnetic cell structure 100 according to FIGS. 1 and 1A, a non-trap,intermediate material 915 may be formed on the another magnetic material713 after the annealed intermediate structure 800 (FIG. 8) has beenformed. The intermediate material 915 may, therefore, comprise, consistessentially of, or consist of a conductive material (e.g., tantalum(Ta)).

Alternatively, with reference to FIG. 9B, according to an embodiment toform the magnetic cell structure 100 according to FIGS. 1 and 1B,another precursor trap material 680′ may be formed instead of theintermediate material 915 of FIG. 9A. In such embodiments, the anothermagnetic material 713 may be characterized as another precursor magneticmaterial 713′ that includes a diffusive species 621′ (FIG. 7A) (e.g.,boron (B)) that may be removed from the another precursor magneticmaterial 713′ by the another precursor trap material 680′. The anotherprecursor trap material 680′ may be formed on the another precursormagnetic material 713′ prior to annealing, such that an annealedstructure segment 900″ (FIG. 9C) may include another depleted magneticmaterial 820′ (FIG. 9C) formed from the another precursor magneticmaterial 713′. The annealed structure segment 900″ also includes anotheramorphous enriched trap material 682′ proximate to the another depletedmagnetic material 820′.

The remaining materials of the magnetic cell structure (e.g., themagnetic cell structure 100 (FIGS. 1, 1A, 1B)) may be fabricated overthe intermediate material 915, according to the embodiment of FIG. 9A,or over the another enriched trap material 682′, according to theembodiment of FIGS. 9B and 9C, to form a precursor structure 900 (FIG.9A) or 900′ (FIG. 9B), respectively. For example, materials 917, such asalternating magnetic material 918 and coupler material 919, may beformed on the intermediate material 915 (FIG. 9A) or on the anotherenriched trap material 682′ (FIG. 9C). For example, and withoutlimitation, the materials 917 may comprise, consist essentially of, orconsist of cobalt/palladium (Co/Pd) multi-sub-regions; cobalt/platinum(Co/Pt) multi-sub-regions; cobalt/nickel (Co/Ni) multi-sub-regions;cobalt/iron/terbium (Co/Fe/Tb) based materials, L₁O materials, couplermaterials, or other magnetic materials of conventional fixed regions.Thus, the fixed region 110′ (FIG. 1A) or 110″ (FIG. 1B), respectively,may include the electrode-adjacent portion 117 (FIGS. 1A and 1B) formedfrom the materials 917. The fixed region 110′ (FIG. 1A) or 110″ (FIG.1B) may also include the intermediate portion 115 (FIG. 1A) or theanother trap region 182 (FIG. 1B) formed from the intermediate material915 or the another enriched trap material 682′, respectively, and theoxide-adjacent portion 113 (FIG. 1A) or 114 (FIG. 1B) formed from theanother precursor magnetic material 713 (FIG. 9A) or the anotherdepleted magnetic material 820′ (FIG. 9C), respectively.

In some embodiments, optionally, one or more upper intermediarymaterials 950 may be formed over the materials 917 for theelectrode-adjacent portion 117 of the fixed region 110′ (FIG. 1A), 110″(FIG. 1B). The upper intermediary materials 950, which, if included,form the optional upper intermediary regions 150 (FIG. 1), may comprise,consist essentially of, or consist of materials configured to ensure adesired crystal structure in neighboring materials. The upperintermediary materials 950 may alternatively or additionally includemetal materials configured to aid in patterning processes duringfabrication of the magnetic cell, barrier materials, or other materialsof conventional STT-MRAM cell core structures. In some embodiments, theupper intermediary material 950 may include a conductive material (e.g.,one or more materials such as copper, tantalum, titanium, tungsten,ruthenium, tantalum nitride, or titanium nitride) to be formed into aconductive capping region.

Another conductive material 904, from which the upper electrode 104(FIG. 1) may be formed, may be formed over the materials 917 for theelectrode-adjacent portion 117 of the fixed region 110′ (FIG. 1A), 110″(FIG. 1B) and, if present, the upper intermediary materials 950. In someembodiments, the another conductive material 904 and the upperintermediary materials 950, if present, may be integrated with oneanother, e.g., with the upper intermediary materials 950 being lowersub-regions of the conductive material 904.

The precursor structure 900 (FIG. 9A), 900′ (FIG. 9B) may then bepatterned, in one or more stages, to form the magnetic cell structure100, according to the embodiment illustrated in FIGS. 1 and 1A or inFIGS. 1 and 1B, respectively. Techniques for patterning structures suchas the precursor structure 900 (FIG. 9A), 900′ (FIG. 9B) to formstructures such as the magnetic cell structure 100 (FIGS. 1, 1A, and 1B)are known in the art and so are not described herein in detail.

After patterning, the magnetic cell structure 100 includes the magneticcell core 101 including the trap region 180 proximate to the free region120 and, in the embodiment of FIG. 1B, the another trap region 182proximate to the fixed region 110″. The free region 120 includes thedepleted magnetic material 820 (FIG. 8), formed from the precursormagnetic material 720 (FIG. 7) and comprises a lower concentration ofthe diffusive species 621′ (FIG. 7A) than a free region formed from theprecursor magnetic material 720 (FIG. 7) without the trap region 180proximate thereto. Moreover, according to the embodiment of FIG. 1B, thefixed region 110″, including the another depleted magnetic material 820′(FIG. 9C) in the oxide-adjacent portion 114 formed from the anotherprecursor magnetic material 713′ (FIG. 9B), comprises a lowerconcentration of the diffusive species 621′ (FIG. 7A) than a fixedregion formed from the another precursor magnetic material 713′ (FIG.9B) without the another trap region 182 proximate thereto.

In some embodiments, the magnetic region or regions (e.g., the freeregion 120, the fixed region 110″ (FIG. 1B)) proximate to the trapregion or regions (e.g., the trap region 180, the another trap region182 (FIG. 1B)) may be substantially or completely depleted of thediffusive species 621′. In other embodiments, the magnetic region orregions may be partially depleted of the diffusive species 621′. In suchembodiments, the magnetic region or regions may have a gradient of thediffusive species 621′ (e.g., boron) therethrough, with a lowconcentration of the diffusive species 621′ adjacent to the trap region180 and a high concentration of the diffusive species 621′ opposite thetrap region 180, relative to one another. The concentration of thediffusive species 621′ may, in some embodiments, equilibrate after orduring anneal.

The free region 120, or other magnetic region (e.g., the oxide-adjacentportion 114 of the fixed region 110″ (FIG. 1B)), formed with acrystalline, depleted magnetic material 820 (FIG. 8), or other depletedmagnetic material, may have a desired crystal structure that may besubstantially free of defects, due, at least in part, to the removal ofthe diffusive species 621′ and the bonding of the diffused species 621to what were the trap sites 687 (FIG. 6D) and due, at least in part, tothe amorphous microstructure of the trap region 180 (or the another trapregion 182).

The crystallinity of the free region 120 may enable the magnetic cellstructure 100 to exhibit a high TMR during use and operation.Furthermore, the depleted magnetic material 820 of the free region 120may promote MA-inducement with a neighboring oxide region (e.g., thesecondary oxide region 270 and the intermediate oxide region 130).

Moreover, in embodiments in which the free region 120 is disposedbetween dual oxide regions (e.g., the intermediate oxide region 130 andthe secondary oxide region 270 of FIG. 2), high MA strength may befurther promoted due to MA-inducement from both of the dual oxideregions. In such embodiments, MA may be induced along the surface of thefree region 120 proximate to the secondary oxide region 270, even withthe trap region 180 disposed between the free region 120 and thesecondary oxide region 270. The amount of precursor trap material 680(FIG. 7) used to form the trap region 180 may be tailored to be of anamount sufficient to effect removal of at least some of the diffusivespecies 621′ (FIG. 7A) from the precursor magnetic material 720 (FIG.7A) while also being an amount not so substantial as to inhibit MAinducement between the secondary oxide region 270 and the free region120.

Accordingly, disclosed is a method of forming a magnetic memory cell.The method comprises forming a precursor structure. Forming theprecursor structure comprises forming a precursor trap materialcomprising trap sites over a substrate. Forming the precursor structurealso comprises forming a precursor magnetic material comprising adiffusive species adjacent to the precursor trap material. The diffusivespecies is transferred from the precursor magnetic material to theprecursor trap material to convert at least a portion of the precursormagnetic material into a depleted magnetic material and to convert atleast a portion of the precursor trap material into an enriched trapmaterial. After the transferring, a magnetic cell core structure isformed from the precursor structure.

Magnetic cell structure 400 of FIG. 4A includes the magnetic cell core401 that may be characterized as an inversion of the magnetic cell core101 of FIGS. 1 and 1A. The magnetic cell structure 400 of FIG. 4A may befabricated by forming and patterning the materials of the magnetic cellstructure 400 from the substrate 102 upwards, with at least one annealsubsequent to forming the precursor trap material 680 (FIG. 6) for thetrap region 480 overlying the free region 420.

Magnetic cell structure 400′ of FIG. 4B includes the magnetic cell core401′ that may be characterized as an inversion of the magnetic cell core101 of FIGS. 1 and 1B. The magnetic cell structure 400′ of FIG. 4B maybe fabricated by forming and patterning the materials of the magneticcell structure 400′ from the substrate 102 upwards, with at least oneanneal subsequent to forming the precursor trap material 680 (FIG. 6)for the trap region 480 overlying the free region 420. Optionally, anintermediate anneal may be performed after forming the another precursormagnetic material 713′ (FIG. 9B) for the oxide-adjacent portion 414 ofthe fixed region 410′.

The magnetic cell structure 500 of FIG. 5 includes the magnetic cellcore 501 that may be characterized as an inversion of the magnetic cellcore 201 of FIG. 2. The magnetic cell structure 500 of FIG. 5 may befabricated by forming and patterning the materials of the magnetic cellstructure 500 from the substrate 102 upwards, with at least one annealsubsequent to forming the precursor trap material 680 (FIG. 6) for thetrap region 480. Optionally, an intermediate anneal may be performedafter forming the another precursor magnetic material 713′ (FIG. 9B) ofthe oxide-adjacent portion 414 of the fixed region 410′.

Accordingly disclosed is a method of forming a semiconductor structure.The method comprises forming an amorphous precursor magnetic materialcomprising at least one diffusive species over a substrate. A precursortrap material comprising an attracter species having at least one trapsite is formed proximate the amorphous precursor magnetic material. Theamorphous precursor magnetic material and the precursor trap materialare annealed to react the diffusive species with the at least one trapsite of the attracter species.

With reference to FIG. 10, illustrated is an STT-MRAM system 1000 thatincludes peripheral devices 1012 in operable communication with anSTT-MRAM cell 1014, a grouping of which may be fabricated to form anarray of memory cells in a grid pattern including a number of rows andcolumns, or in various other arrangements, depending on the systemrequirements and fabrication technology. The STT-MRAM cell 1014 includesa magnetic cell core 1002, an access transistor 1003, a conductivematerial that may function as a data/sense line 1004 (e.g., a bit line),a conductive material that may function as an access line 1005 (e.g., aword line), and a conductive material that may function as a source line1006. The peripheral devices 1012 of the STT-MRAM system 1000 mayinclude read/write circuitry 1007, a bit line reference 1008, and asense amplifier 1009. The cell core 1002 may be any one of the magneticcell cores (e.g., the magnetic cell cores 101 (FIG. 1), 201 (FIG. 2),401 (FIG. 4A), 401′ (FIG. 4B), 501 (FIG. 5)) described above. Due to thestructure of the cell core 1002, the method of fabrication, or both, theSTT-MRAM cell 1014 may have a high TMR and a high MA strength.

In use and operation, when an STT-MRAM cell 1014 is selected to beprogrammed, a programming current is applied to the STT-MRAM cell 1014,and the current is spin-polarized by the fixed region of the cell core1002 and exerts a torque on the free region of the cell core 1002, whichswitches the magnetization of the free region to “write to” or “program”the STT-MRAM cell 1014. In a read operation of the STT-MRAM cell 1014, acurrent is used to detect the resistance state of the cell core 1002.

To initiate programming of the STT-MRAM cell 1014, the read/writecircuitry 1007 may generate a write current (i.e., a programmingcurrent) to the data/sense line 1004 and the source line 1006. Thepolarity of the voltage between the data/sense line 1004 and the sourceline 1006 determines the switch in magnetic orientation of the freeregion in the cell core 1002. By changing the magnetic orientation ofthe free region with the spin polarity, the free region is magnetizedaccording to the spin polarity of the programming current, theprogrammed logic state is written to the STT-MRAM cell 1014.

To read the STT-MRAM cell 1014, the read/write circuitry 1007 generatesa read voltage to the data/sense line 1004 and the source line 1006through the cell core 1002 and the access transistor 1003. Theprogrammed state of the STT-MRAM cell 1014 relates to the electricalresistance across the cell core 1002, which may be determined by thevoltage difference between the data/sense line 1004 and the source line1006. In some embodiments, the voltage difference may be compared to thebit line reference 1008 and amplified by the sense amplifier 1009.

FIG. 10 illustrates one example of an operable STT-MRAM system 1000. Itis contemplated, however, that the magnetic cell cores 101 (FIG. 1), 201(FIG. 2), 401 (FIG. 4A), 401′ (FIG. 4B), 501 (FIG. 5) may beincorporated and utilized within any STT-MRAM system configured toincorporate a magnetic cell core having magnetic regions.

Accordingly, disclosed is a semiconductor device comprising a spintorque transfer magnetic random memory (STT-MRAM) array comprisingSTT-MRAM cells. At least one STT-MRAM cell of the STT-MRAM cellscomprises a crystalline magnetic region over a substrate. Thecrystalline magnetic region exhibits a switchable magnetic orientation.A crystalline oxide region is adjacent the crystalline magnetic region.A magnetic region, exhibiting a substantially fixed magneticorientation, is spaced from the crystalline magnetic region by thecrystalline oxide region. An amorphous trap region is adjacent thecrystalline magnetic region. The amorphous trap region comprises aspecies diffused from a precursor magnetic material of the crystallinemagnetic region and bonded to an attracter species of a precursor trapmaterial of the amorphous trap region. The precursor magnetic materialhad trap sites at which the species, diffused from the precursormagnetic material, is bonded to the attracter species in the amorphoustrap region.

With reference to FIG. 11, illustrated is a simplified block diagram ofa semiconductor device 1100 implemented according to one or moreembodiments described herein. The semiconductor device 1100 includes amemory array 1102 and a control logic component 1104. The memory array1102 may include a plurality of the STT-MRAM cells 1014 (FIG. 10)including any of the magnetic cell cores 101 (FIG. 1), 201 (FIG. 2), 401(FIG. 4A), 401′ (FIG. 4B), 501 (FIG. 5) discussed above, which magneticcell cores 101 (FIG. 1), 201 (FIG. 2), 401 (FIG. 4A), 401′ (FIG. 4B),501 (FIG. 5) may have been formed according to a method described aboveand may be operated according to a method described above. The controllogic component 1104 may be configured to operatively interact with thememory array 1102 so as to read from or write to any or all memory cells(e.g., STT-MRAM cell 1014 (FIG. 10)) within the memory array 1102.

With reference to FIG. 12, depicted is a processor-based system 1200.The processor-based system 1200 may include various electronic devicesmanufactured in accordance with embodiments of the present disclosure.The processor-based system 1200 may be any of a variety of types such asa computer, pager, cellular phone, personal organizer, control circuit,or other electronic device. The processor-based system 1200 may includeone or more processors 1202, such as a microprocessor, to control theprocessing of system functions and requests in the processor-basedsystem 1200. The processor 1202 and other subcomponents of theprocessor-based system 1200 may include magnetic memory devicesmanufactured in accordance with embodiments of the present disclosure.

The processor-based system 1200 may include a power supply 1204 inoperable communication with the processor 1202. For example, if theprocessor-based system 1200 is a portable system, the power supply 1204may include one or more of a fuel cell, a power scavenging device,permanent batteries, replaceable batteries, and rechargeable batteries.The power supply 1204 may also include an AC adapter; therefore, theprocessor-based system 1200 may be plugged into a wall outlet, forexample. The power supply 1204 may also include a DC adapter such thatthe processor-based system 1200 may be plugged into a vehicle cigarettelighter or a vehicle power port, for example.

Various other devices may be coupled to the processor 1202 depending onthe functions that the processor-based system 1200 performs. Forexample, a user interface 1206 may be coupled to the processor 1202. Theuser interface 1206 may include input devices such as buttons, switches,a keyboard, a light pen, a mouse, a digitizer and stylus, a touchscreen, a voice recognition system, a microphone, or a combinationthereof. A display 1208 may also be coupled to the processor 1202. Thedisplay 1208 may include an LCD display, an SED display, a CRT display,a DLP display, a plasma display, an OLED display, an LED display, athree-dimensional projection, an audio display, or a combinationthereof. Furthermore, an RF sub-system/baseband processor 1210 may alsobe coupled to the processor 1202. The RF sub-system/baseband processor1210 may include an antenna that is coupled to an RF receiver and to anRF transmitter (not shown). A communication port 1212, or more than onecommunication port 1212, may also be coupled to the processor 1202. Thecommunication port 1212 may be adapted to be coupled to one or moreperipheral devices 1214, such as a modem, a printer, a computer, ascanner, or a camera, or to a network, such as a local area network,remote area network, intranet, or the Internet, for example.

The processor 1202 may control the processor-based system 1200 byimplementing software programs stored in the memory. The softwareprograms may include an operating system, database software, draftingsoftware, word processing software, media editing software, or mediaplaying software, for example. The memory is operably coupled to theprocessor 1202 to store and facilitate execution of various programs.For example, the processor 1202 may be coupled to system memory 1216,which may include one or more of spin torque transfer magnetic randomaccess memory (STT-MRAM), magnetic random access memory (MRAM), dynamicrandom access memory (DRAM), static random access memory (SRAM),racetrack memory, and other known memory types. The system memory 1216may include volatile memory, non-volatile memory, or a combinationthereof. The system memory 1216 is typically large so that it can storedynamically loaded applications and data. In some embodiments, thesystem memory 1216 may include semiconductor devices, such as thesemiconductor device 1100 of FIG. 11, memory cells including any of themagnetic cell cores 101 (FIG. 1), 201 (FIG. 2), 401 (FIG. 4A), 401′(FIG. 4B), 501 (FIG. 5) described above, or a combination thereof.

The processor 1202 may also be coupled to non-volatile memory 1218,which is not to suggest that system memory 1216 is necessarily volatile.The non-volatile memory 1218 may include one or more of STT-MRAM, MRAM,read-only memory (ROM) such as an EPROM, resistive read-only memory(RROM), and flash memory to be used in conjunction with the systemmemory 1216. The size of the non-volatile memory 1218 is typicallyselected to be just large enough to store any necessary operatingsystem, application programs, and fixed data. Additionally, thenon-volatile memory 1218 may include a high-capacity memory such as diskdrive memory, such as a hybrid-drive including resistive memory or othertypes of non-volatile solid-state memory, for example. The non-volatilememory 1218 may include semiconductor devices, such as the semiconductordevice 1100 of FIG. 11, memory cells including any of the magnetic cellcores 101 (FIG. 1), 201 (FIG. 2), 401 (FIG. 4A), 401′ (FIG. 4B), 501(FIG. 5) described above, or a combination thereof.

While the present disclosure is susceptible to various modifications andalternative forms in implementation thereof, specific embodiments havebeen shown by way of example in the drawings and have been described indetail herein. However, the present disclosure is not intended to belimited to the particular forms disclosed. Rather, the presentdisclosure encompasses all modifications, combinations, equivalents,variations, and alternatives falling within the scope of the presentdisclosure as defined by the following appended claims and their legalequivalents.

What is claimed is:
 1. A method of forming an electronic device, themethod comprising: forming a precursor structure, comprising: forming aprecursor trap material comprising trap sites over an electrode, formingthe precursor trap material over the electrode comprising: forming amaterial structure comprising sub-regions of an attractor speciesalternating with sub-regions of at least one other attractor species,the material structure comprising trap sites of one or more of theattractor species and the at least one other attractor species, the trapsites disposed at least along interfaces between the sub-regions of theattractor species and the sub-regions of the at least one otherattractor species; and forming a precursor magnetic material comprisinga diffusive species adjacent to the precursor trap material; andtransferring the diffusive species from the precursor magnetic materialto the precursor trap material and reacting the diffusive species withthe trap sites of at least one of the attractor species and the at leastone other attractor species to convert at least a portion of theprecursor magnetic material into a depleted magnetic material and toconvert at least a portion of the precursor trap material into anenriched trap material; and after the transferring, forming a magneticcell core structure from the precursor structure.
 2. The method of claim1, further comprising bombarding the material structure to disruptattached bonds of the material structure and form additional trap sites.3. The method of claim 1, wherein: forming the precursor trap materialover the electrode comprises forming the precursor trap material over aconductive material; and forming the precursor magnetic materialadjacent to the precursor trap material comprises forming the precursormagnetic material over the precursor trap material.
 4. The method ofclaim 3, further comprising, before the transferring, forming an oxidematerial over the precursor magnetic material.
 5. The method of claim 4,further comprising, after forming the oxide material, forming anothermagnetic material over the oxide material.
 6. The method of claim 1,wherein transferring the diffusive species from the precursor magneticmaterial to the precursor trap material comprises transferring boronfrom the precursor magnetic material to the precursor trap material. 7.The method of claim 1, wherein converting at least the portion of theprecursor trap material into the enriched trap material comprisesforming an enriched trap material comprising: at least one of tungsten,hafnium, molybdenum, or zirconium; at least one of iron, cobalt,ruthenium, or nickel; and the diffusive species.
 8. A method of formingan electronic device, the method comprising: forming a precursorstructure, comprising: forming a precursor trap material comprising trapsites over an electrode, forming the precursor trap material comprising:forming an attractor species over the electrode; and bombarding theattractor species to disrupt attached bonds of the attractor species andform the trap sites; forming a precursor magnetic material comprising adiffusive species adjacent to the precursor trap material; andtransferring the diffusive species from the precursor magnetic materialto the precursor trap material, transferring the diffusive speciescomprising diffusing the diffusive species into the precursor trapmaterial and reacting the diffusive species with the trap sites toconvert at least a portion of the precursor magnetic material into adepleted magnetic material and to convert at least a portion of theprecursor trap material into an enriched trap material; and after thetransferring, forming a magnetic cell core structure from the precursorstructure.
 9. The method of claim 8, wherein transferring the diffusivespecies from the precursor magnetic material to the precursor trapmaterial comprises annealing the precursor magnetic material.
 10. Themethod of claim 9, wherein annealing comprises annealing at atemperature of greater than about 500° C.
 11. The method of claim 9,wherein annealing comprises converting a microstructure of the precursortrap material from a crystalline microstructure to an amorphousmicrostructure.
 12. The method of claim 8, wherein forming the precursortrap material comprising trap sites over the electrode comprises formingthe precursor trap material comprising at least of tungsten, hafnium,molybdenum, or zirconium and at least one of iron, cobalt, ruthenium, ornickel over the electrode.
 13. The method of claim 8, wherein formingthe precursor trap material comprises forming the precursor trapmaterial having a thickness between about 10 Å and about 100 Å.